1. Field of the Invention
The invention relates to a pixel structure and a manufacturing method thereof. More particularly, the invention relates to a pixel structure having a polysilicon thin film transistor (TFT) and a manufacturing method of the pixel structure.
2. Description of Related Art
A TFT is a driving element applicable to a display. Among the TFTs, a low temperature polysilicon (LTPS) TFT is an element different from the conventional amorphous silicon TFT. Since the electron mobility of the LTPS-TFT can reach 200 cm2/V-sec or more, TFTs with small dimension can be fabricated, and the aperture ratio can then be increased. Furthermore, the luminosity of the display device is increased, and the power consumption is reduced.
In a normal polysilicon TFT, a channel region, a source region, and a drain region are formed in an island-like polysilicon pattern. The island-like polysilicon pattern is covered by a gate insulating layer, and a gate is then formed on the gate insulating layer. Wherein the gate insulating layer within a uniformly thickness. The island-like polysilicon pattern has a certain height (i.e., a certain thickness), and therefore the gate insulating layer may have undesired step coverage due to the height of side walls of the island-like polysilicon pattern. As such, current leakage may occur between the gate and the island-like polysilicon pattern.